1 files changed, 80 insertions, 26 deletions

diff --git a/include/grpc++/impl/codegen/sync_stream.h b/include/grpc++/impl/codegen/sync_stream.h
index 4d9b074e95..ae3b8e441d 100644
--- a/include/grpc++/impl/codegen/sync_stream.h
+++ b/include/grpc++/impl/codegen/sync_stream.h
@@ -100,22 +100,40 @@ class WriterInterface {
  public:
   virtual ~WriterInterface() {}
 
-  /// Blocking write \a msg to the stream with options.
+  /// Blocking write \a msg to the stream with WriteOptions \a options.
   /// This is thread-safe with respect to \a Read
   ///
   /// \param msg The message to be written to the stream.
-  /// \param options Options affecting the write operation.
+  /// \param options The WriteOptions affecting the write operation.
   ///
   /// \return \a true on success, \a false when the stream has been closed.
-  virtual bool Write(const W& msg, const WriteOptions& options) = 0;
+  virtual bool Write(const W& msg, WriteOptions options) = 0;
 
-  /// Blocking write \a msg to the stream with default options.
+  /// Blocking write \a msg to the stream with default write options.
   /// This is thread-safe with respect to \a Read
   ///
   /// \param msg The message to be written to the stream.
   ///
   /// \return \a true on success, \a false when the stream has been closed.
   inline bool Write(const W& msg) { return Write(msg, WriteOptions()); }
+
+  /// Write \a msg and coalesce it with the writing of trailing metadata, using
+  /// WriteOptions \a options.
+  ///
+  /// For client, WriteLast is equivalent of performing Write and WritesDone in
+  /// a single step. \a msg and trailing metadata are coalesced and sent on wire
+  /// by calling this function.
+  /// For server, WriteLast buffers the \a msg. The writing of \a msg is held
+  /// until the service handler returns, where \a msg and trailing metadata are
+  /// coalesced and sent on wire. Note that WriteLast can only buffer \a msg up
+  /// to the flow control window size. If \a msg size is larger than the window
+  /// size, it will be sent on wire without buffering.
+  ///
+  /// \param[in] msg The message to be written to the stream.
+  /// \param[in] options The WriteOptions to be used to write this message.
+  void WriteLast(const W& msg, WriteOptions options) {
+    Write(msg, options.set_last_message());
+  }
 };
 
 /// Client-side interface for streaming reads of message of type \a R.
@@ -213,11 +231,13 @@ class ClientWriter : public ClientWriterInterface<W> {
     finish_ops_.RecvMessage(response);
     finish_ops_.AllowNoMessage();
 
-    CallOpSet<CallOpSendInitialMetadata> ops;
-    ops.SendInitialMetadata(context->send_initial_metadata_,
-                            context->initial_metadata_flags());
-    call_.PerformOps(&ops);
-    cq_.Pluck(&ops);
+    if (!context_->initial_metadata_corked_) {
+      CallOpSet<CallOpSendInitialMetadata> ops;
+      ops.SendInitialMetadata(context->send_initial_metadata_,
+                              context->initial_metadata_flags());
+      call_.PerformOps(&ops);
+      cq_.Pluck(&ops);
+    }
   }
 
   void WaitForInitialMetadata() {
@@ -230,11 +250,24 @@ class ClientWriter : public ClientWriterInterface<W> {
   }
 
   using WriterInterface<W>::Write;
-  bool Write(const W& msg, const WriteOptions& options) override {
-    CallOpSet<CallOpSendMessage> ops;
+  bool Write(const W& msg, WriteOptions options) override {
+    CallOpSet<CallOpSendInitialMetadata, CallOpSendMessage,
+              CallOpClientSendClose>
+        ops;
+
+    if (options.is_last_message()) {
+      options.set_buffer_hint();
+      ops.ClientSendClose();
+    }
+    if (context_->initial_metadata_corked_) {
+      ops.SendInitialMetadata(context_->send_initial_metadata_,
+                              context_->initial_metadata_flags());
+      context_->set_initial_metadata_corked(false);
+    }
     if (!ops.SendMessage(msg, options).ok()) {
       return false;
     }
+
     call_.PerformOps(&ops);
     return cq_.Pluck(&ops);
   }
@@ -293,11 +326,13 @@ class ClientReaderWriter final : public ClientReaderWriterInterface<W, R> {
   ClientReaderWriter(ChannelInterface* channel, const RpcMethod& method,
                      ClientContext* context)
       : context_(context), call_(channel->CreateCall(method, context, &cq_)) {
-    CallOpSet<CallOpSendInitialMetadata> ops;
-    ops.SendInitialMetadata(context->send_initial_metadata_,
-                            context->initial_metadata_flags());
-    call_.PerformOps(&ops);
-    cq_.Pluck(&ops);
+    if (!context_->initial_metadata_corked_) {
+      CallOpSet<CallOpSendInitialMetadata> ops;
+      ops.SendInitialMetadata(context->send_initial_metadata_,
+                              context->initial_metadata_flags());
+      call_.PerformOps(&ops);
+      cq_.Pluck(&ops);
+    }
   }
 
   void WaitForInitialMetadata() override {
@@ -325,9 +360,24 @@ class ClientReaderWriter final : public ClientReaderWriterInterface<W, R> {
   }
 
   using WriterInterface<W>::Write;
-  bool Write(const W& msg, const WriteOptions& options) override {
-    CallOpSet<CallOpSendMessage> ops;
-    if (!ops.SendMessage(msg, options).ok()) return false;
+  bool Write(const W& msg, WriteOptions options) override {
+    CallOpSet<CallOpSendInitialMetadata, CallOpSendMessage,
+              CallOpClientSendClose>
+        ops;
+
+    if (options.is_last_message()) {
+      options.set_buffer_hint();
+      ops.ClientSendClose();
+    }
+    if (context_->initial_metadata_corked_) {
+      ops.SendInitialMetadata(context_->send_initial_metadata_,
+                              context_->initial_metadata_flags());
+      context_->set_initial_metadata_corked(false);
+    }
+    if (!ops.SendMessage(msg, options).ok()) {
+      return false;
+    }
+
     call_.PerformOps(&ops);
     return cq_.Pluck(&ops);
   }
@@ -423,7 +473,10 @@ class ServerWriter final : public ServerWriterInterface<W> {
   }
 
   using WriterInterface<W>::Write;
-  bool Write(const W& msg, const WriteOptions& options) override {
+  bool Write(const W& msg, WriteOptions options) override {
+    if (options.is_last_message()) {
+      options.set_buffer_hint();
+    }
     CallOpSet<CallOpSendInitialMetadata, CallOpSendMessage> ops;
     if (!ops.SendMessage(msg, options).ok()) {
       return false;
@@ -485,7 +538,10 @@ class ServerReaderWriterBody final {
     return call_->cq()->Pluck(&ops) && ops.got_message;
   }
 
-  bool Write(const W& msg, const WriteOptions& options) {
+  bool Write(const W& msg, WriteOptions options) {
+    if (options.is_last_message()) {
+      options.set_buffer_hint();
+    }
     CallOpSet<CallOpSendInitialMetadata, CallOpSendMessage> ops;
     if (!ops.SendMessage(msg, options).ok()) {
       return false;
@@ -523,7 +579,7 @@ class ServerReaderWriter final : public ServerReaderWriterInterface<W, R> {
   bool Read(R* msg) override { return body_.Read(msg); }
 
   using WriterInterface<W>::Write;
-  bool Write(const W& msg, const WriteOptions& options) override {
+  bool Write(const W& msg, WriteOptions options) override {
     return body_.Write(msg, options);
   }
 
@@ -562,8 +618,7 @@ class ServerUnaryStreamer final
   }
 
   using WriterInterface<ResponseType>::Write;
-  bool Write(const ResponseType& response,
-             const WriteOptions& options) override {
+  bool Write(const ResponseType& response, WriteOptions options) override {
     if (write_done_ || !read_done_) {
       return false;
     }
@@ -604,8 +659,7 @@ class ServerSplitStreamer final
   }
 
   using WriterInterface<ResponseType>::Write;
-  bool Write(const ResponseType& response,
-             const WriteOptions& options) override {
+  bool Write(const ResponseType& response, WriteOptions options) override {
     return read_done_ && body_.Write(response, options);
   }